The bumper of a railroad car or the like must have at least one shock-absorbing spring engaged between the bumper and the vehicle body, so the two can move relatively without damage. Thus the spring allows the bumper to be pushed in, damping any sudden shock and transmitting it smoothly to the vehicle.
A typical such system is seen in U.S. Pat. No. 4,076,226 of C. Anolick where two relatively movable parts carry parallel spaced pins that are moved apart when the one part is pushed toward the other. A lapped belt of an oriented elastomer is looped over the two parts to absorb and cushion the shock when these parts are pushed together.
This arrangement is fairly bulky. In particular it is fairly long, occupying considerable space behind the vehicle body. Thus it is inappropriate for use in a railroad-car bumper, which necessitates a fairly stubby spring arrangement which must lie wholly outside the car.